Composite roadway and the process of constructing the same.



No. 842,201. -PATENTED JAN. 29, 1907. *y S. G. HoWB. COMPOSITE ROADWAYAND THE PROCESS 0F SONSTRUSTING THB SAMSl APPLICATION FILED AUG.15.1906.

INVENTDH fg/2 with a layer oi' foundation ii ililili @il SOLON G. HUWE,OF

narnnfr einden.)

DETROIT, MICHIGAN.

Specification of Letters Patent.

Patented.I Jan. 29, 1907.

Application filed August 15, 1906. Serial No. 330.693.

le it known that l, SoLoN G. Howe, a citizen of the United States,residing at Detroit, county Iof Wayne, State of Michigan, have inventeda certain new and useful lmproveincnt in Composite Roadways and theProcesses of Constructing the Same, of which the following is aspeciiication, reference being had to the accompanying drawings, whichform a part of this specification.

My invention has for its object an improved composite roadway and theprocess of constructing the saine, the invention being adapted forcountryr roads and city streets, the roadway being of superiorconstruction, economy, and utility; and it consists of the constructionand the process of forming the same hereinafter described and claimed,and illustrated in the accompanying drawings, in which- Figure l.illustrates in Vertical cross-section my invention as applied to a citypavement. Fig. 2 is a similar view showing 'my invention as applied toaI country road. Fig. 2 is a fragmentary enlarged view.

My improved composite roadway consists, essentially, of two layers,formed and applied as hereinafter described.

F or a country road, for example, where no curb is required my inventioncontemplates' iirst digging a trench of suitablel depth-say a depth often inches-the trench being of any desired width for the roadway, givingthe subgrade or bed a suiii cientA curvature or crown to insure a properdrainage. The subgrade or bed is then rolled with a heavy roller until-a d esired degree of compactness is attained. '.lhis compactness mayreadily be tested, as with a pointed steel prod, and should spots be yfound not of a proper density or firmness my invention contemplatescovering said spots composition, hereinafter set forth, then compressingthe same by rolling or tamping until a proper iirinness is obtained.Next upon tins subgrade or bed my invention contemplates spreading aseepy foundation layer-z'. e.. a

layer through which wat-er will flow gently or slowlyin other words, alayer in which water will seep or ooze through said layercomposed of amixture, hereinafterdescribed,

spread over the subgrade to a suitable depth-as, for example, a depth ofsix inches after being properly rolled and compacted. Upon thisfoundation layer I spread an upper surface course or layer formed of adifferent mixture, as herein set forth.

My foundation mixture or layer is come ,l posed of crushed stone, as ofcrushed cobblel stone, where the saine is obtainable,v although otherkinds of crushed stone may be utilized, as crushed granite, trap-rock,or limestone, as they" may be more easily ob tained, i

The crushed stones are to be crushed to one to two and one-half inchesin largest dimensions.

ing screened are then brought to the trench any suitable manner by handor by machine with a su icient supply of sharp coarse sand low a half aninch in size, or thereabout, the gravel and sand being a little morethan upper layer or wearing course.V

Tite top or wearing course ris composed of crushed gravel or other stoneof irregular slapc of smaller dimensions than the crushed stone used inthe lower or foundation course, the gravel-stoms bcingcrushed,preferably, to aboutonc-lialf to one inch' in largest size. Ground clay,preferably ferruginous clay, is mixed wi th a suii'ieient supply ofwater added to form a thick mortar,

sullicient quantity to coat the crushedgravel This top layer or bodyafter being spread over the foundation layer is then subjected to heavycompression, as by a roller, whereby the clay mortar will be thoroughlycom pressed intoall the spaces between the finely-crushed gravelor'stone,this upper course or layer constituting the wearing-surfaceofthe roadway. The .clay mortar will also be forced in the operation oflaying the roadway onto the exposed surfaces of the foundation layer, asupon -the exposed surfaces of the larger l give sizes varying, forexample, from about' The crushed stones after b e-A enough to thoroughlyfill the space or voidsv a rough'ened surface for the reception of theafter wlieh tlie crusled stone is added to the .I clay mortar. l 'll'eclay mortar should be of or stone and thoroughly iill the intersizices.

where theroadway is to be laid and mixed in anzi gravel, the gravelbeing preferably be- IOO ies

broken stone at the 'top of the foundation layer, farming a Iirm bondbetween the top and the foundation vlayers or courses. The

top or wearing surface may be made of any desired'depth, a depth of fourinches after compression beingv a very suitable depth. The road -bedbelow the foundation-layer may, if necessary, as already described haveany spots found to be not of proper density or firmness provided with alilling mixture similar to that of the foundation mixturefor example,the same being rolled or tamped down until all loose or Softspots areremedied, so as to obtain a thoroughly firm seepy bed. The rmness of theupper course or layer can be readily tested after rolling by a steelprod, as also the foundation layer, so as to make certain that eachlayer is of proper density vand firmness.4 For a street-pavement Atheprocess of construction is essentially the same, with the addition of acurb and a suitable base and back for the curb.

In the drawings, a represents the road-bed of earth below thefoundation' course above described. b denotes the foundation layer, ofcoarser crushed stonepsand, and gravel, and c the top or wearing courseol' more finely crushed gravel or stone mixed with clay mortar. In theenlarged view Fig. 3, d represents the coarser crushed stone, e theparticles of sand, and f the particles of gravel of the foundationlayer, the sand and gravel being shown in the interstice between thebroken particles of stone d. In Fig. 3 also the more finely crushedgravel or stone of the wearing surface or layer is indicated at g, theclay mortar being indicated at z filling the interstices between theparticles of crushed stone g and coating said particles. In Fig. 1, 'idenotes a suitable curb of any desired construction, and j a concretebase and back for the curb. The construction of the roadway and theprocess of forming the same will now be clearly understood.

The advantages of this composite roadway are many ,and will be evident,as follows: For' a country roadway where no curbing is desired guttersit' may readily be formed, as by a supplementary roller attached to theside of the compression-roller. A vspecial advantage of such a compositeroadway is that it is comparatively inexpensive in construction and iseasily and cheaply maintained. Should any soft spots or depressionsdevelop under heavy traffic, repairs could readily be made by simplyfirst. cleaning such depressions, so as to make as `good a y bond aspossible, and then filling the depression with a mixture such as abovedescribed, constituting the top or wearing course, and rollino Qrtampingthe same firmly into'place. The lhng in the interstices of the crushedstone in the foundation layer inak'es a cushioned foundation for theupper layer or wearing-surface, while the clay mortar in the upfillingthe interstic-es with sharp sandand gravel to form -a lower seepyfoundation course and filling the interstices of the upper course withclay mortar the tendency of the mixture to slip or move out of positionis practically eliminated, and without such movement there would be but'little chance for Wear and creatiqn of dust. The general uniformityofvsizes of the crushed stones in the two courses, respectively, whileinsuring a compactness will not, however,^develop a rigidity in oneplace and a softness or springy condition in another, but theconstruction will insure a body likely to remain firmly and continuouslyintact.. The construction Aof the lower or foundation layer of such aroadway being pervious to water will allow a perfect seepage which willtend to keep the lbody in good condition and with proper subdrainagewhere the soil'underneath the roadway will not properly absorb themoisture will insure a perfect condition at all times.

The clay mortar used as a binder if of a proper consistency will bondthe small irregular-shaped pieces or particles of crushed stoneconstituting the upper or wearing surface of the roadway, the onlyrequisite being a suitable degree of moisture, which when not had byrainfalls can vbe had by sprinkling. This clay binder and crushed stonebody forming the upper layer after a hot day will absorb water readily,so that by passing a sprinkling-cart over it at Sundown the tendencywould be to Very materially cool the atmosphere, and the body wouldabsorb sufficient water over night to maintain a certain degree ofdampness and eliminate the formation of dust on the surface during thefollowing day. Such a seepage of Water as I provide 1n my foundationlayer in other kinds of pavement are detrimental, and therefore otherforms ofpavement must be made impervious to water in a well-knownmanner. Other kinds of pavement laid upon a customary concretefoundation are supposed to be mipervious to water, thereby lexcluding;the allowance of water and air needed for shadetrees on the sides of thestreets.

l/Vhat I claim as my invention-is 1. A composite roadway comprising afoundation seepy layer composed of a mixturel of coarsely-crushed stonegravel and substantially as described.

2. A composite roadway comprising a foundation. seepy layer composed ofa mixture pf coarsely-crushed stone gravel and sand spread o ver andcompressedl upon 'the bed of the roadway, and a seepy wearing- -body oruppersurface layer composed of a mixture of more finely crushed stonevand clay mortar spread over and compressed,

upon the foundation body or layer, vthe gravel and sand of thefoundation layerv filling the interstices between the crushed stone,

and the clay mortar coating the crushed stone of the upper layer andfilling the interstices therebetween, whereby water will seep throughthe entire roadway, substantially as described.

3. A composite roadway comprising a foundation layer composed of amixture of coarsely-crushed stone. gravel anda sand s read over andcompressed upon the bed of t ie roadway in a dry condition, and awearing-body or upper surface layer composed of a mixture of morefinely'crushed stone and clay mortar vspread ovenand compressed upon thefoundation layenthe layers of said roadway being pervious to moisture,the

lgravel and sand of the foundation layer forming a seepy cushion, andthe clay mortar of the uplper layer forming a bond, whereby wa 4terwilseep through the entire roadway, sub# stantially as described.

4. The process of constructing a composite roadway consisting of firstmixing coarsel crushed stone gravel and sand 1n a dry con ition,spreading the mixture over and compressing the same upon the road-bed toform a seepy foundation layer, and then spreading upon the foundationlayer amixture of more finely cru shed stone and clay mortar andcompressing the same upon the foundation layer to form an u per seepycourse or wearing-surface, whereiiy water will seep through the entireroadway, substantially as described. 1

roadway consisting of first excavating a trench, compressin the soil andfilling soft places therein wit a previously-prepared mixtureA ofcrushed 'stone gravel and sand compressed thereinto, thenv spreadingthereupon a seepy found ation layer consisting of apreviously-preparedmixture of crushed stone gravel and sand, andcompressing the same in place, and then spreading upon the foun-y dationlayer an upper seepy layer consisting of a previously-prepared mixtureof more finely crushed stone and clay mortar and compressing the sainein place upon the found ation layer, whereby water will seep through theentire roadway, substantially as described. l

. 6. A two -course composite roadwa or pavement comprising a foundationayer composed of 'a previously-prepared mixture of coarsely-crushedstone gravel and sand -spread over and compressed upon the bed of theroadway, and a wearing-body orupper surface layer composed of apreviously-prepared mixture of crushed stone and clay morfoundation bodyor layer, the said layers be ing pervious to moisture whereby water willseep through the entire roadway.

n' In testimony whereof I have signed this ing witnesses. SOLON G. HOWE.

Witnesses:

JAMES F. HILL,

N. S. WRIGHT.

5. The process of constructing a composite l tar spread over and.compressed upon theV specification in the presence of two subscrib-

